Raiser seat

ABSTRACT

A raiser seat for assisting a person from a sitting to a standing position is described. The seat comprises: a seat frame ( 4 ); a seat ( 10 ) supported for movement relative to the seat frame between a lowered position and a raised position; and a movement mechanism for moving the seat between the lowered and the raised positions. The movement mechanism comprises at least one cam ( 104 ) and the seat rests on the at least one cam such that rotation of the at least one cam results in movement of the seat relative to the seat frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/568,599, filed Jan. 3, 2007, now U.S. Pat. No. 7,600,815 which is theU.S. national stage application of International ApplicationPCT/GB2004/003531, filed Aug. 17, 2004, which international applicationwas published on Mar. 3, 2005, as International PublicationWO2005/018522 in the English language. The International Applicationclaims priority of Great Britain Patent Applications 0319533.6,0319526.0 and 0319538.5, filed Aug. 18, 2003.

BACKGROUND

The present application is directed towards raiser seats for assisting aperson from a sitting to a standing position. It is particularly appliedto raiser seats in which the motion of the seat is determined by cams.

A variety of seats which can be raised or lowered in order to assistpeople from a sitting to a standing position are known. These areapplied in many fields, and are of particular use in recovery fromoperations or for people with limited abilities. These seats may be asimple chair, or may also be used in medical transfer chairs, commodesor wheelchairs.

An example of a raiser seat is discussed U.S. Pat. No. 5,513,867(Bloswick et al). This patent relates to a seat-lift wheelchair. Theseat can pivot about its front edge to assist a person in standing up.The lift of the seat is achieved by the action of a tension springpulling on a cable. The cable acts around a cam attached to the bottomof the seat. This cam determines the effective distance of the tensionin the cable from the pivot point in the seat. It therefore allows thetorque to be varied depending on the position of the seat.

This mechanism requires a large tension spring in order to generate therequired torque. It will also only function correctly when the pivotpoint of the seat is fixed relative to the seat frame and the tensionspring.

SUMMARY

The present invention provides a raiser seat in which the seat restsupon cams which are attached to the seat frame. These cams can berotated to lift the seat.

According to a first aspect of the present invention, there is provideda raiser seat for assisting a person from a sitting to a standingposition comprising:

-   -   a seat frame;    -   a seat adapted for movement relative to the seat frame between a        lowered position and a raised position; and    -   a movement mechanism for moving the seat between the lowered and        the raised positions;    -   wherein the movement mechanism comprises at least one cam and        wherein the seat is supported by the at least one cam such that        rotation of the at least one cam results in movement of the seat        relative to the seat frame.

The term “cam” includes single and multiple bladed and lever-type cams.Lever-type cams can have one or more tracks, conveyers,rollers/casters/wheels, roller type or plain bearings, or linear slidesthat act to set the effective profile of the lever, thus achieving thesame function as a cam.

Unlike U.S. Pat. No. 5,513,867, the seat is supported by the cam, ratherthan the cam being fixed to or part of the seat. This means thatrotation of the cam causes the seat to move. During this movement therecan be relative movement between the seat and the cam. The profile ofthe lift (including tilt and/or translation) can be determined accordingto the profile of the cam. In this way the cam is directly responsiblefor movement of the seat, rather than being indirectly responsible formovement of the seat due to the action of a tension cable as in U.S.Pat. No. 5,513,867.

Preferably, the seat forms part of a seat unit. This allows the seat tobe permanently or removably attached to the seat frame, depending on theparticular application.

Preferably, the at least one cam is retained within the seat unit. Thus,the seat and cam can easily be incorporated into a finished seat unit.It also has the advantage that the seat unit can be changed to allowdifferent cam profiles to be used with the same seat frame. In oneembodiment, the at least one cam is rotatably fixed to the seat unit.

Preferably the seat unit comprises at least one reinforcing element. Thereinforcing element acts to increase the rigidity, strength, and generalpracticalities of the seat unit.

Preferably the seat and/or seat unit can be mounted on the seat frame bysliders in one embodiment. Protrusions and/or invasions (grooves) ofdifferent shapes and forms for location of the seat and/or seat unit canalso be used. The seat and/or seat unit can be horizontally orvertically slid or placed in positions. Locking mechanisms can also beprovided.

Preferably, the movement mechanism comprises a pair of coaxial cams.These cams can be located on either side of the seat and thereforespread the load of a person sitting on the seat evenly between them.

Preferably, the movement mechanism comprises a first pair of coaxialcams located supporting a rear end of the seat and a second pair ofcoaxial cams supporting a front end of the seat. By using two pairs ofcams, one towards the rear and one towards the front, the lift profilecan be varied almost infinitely. The profiles of the cams will determinethe movement profile of the seat. This can vary considerably, becausethe use of cams means that a fixed pivot point is not required.

Preferably, the raiser seat further comprises a motor for rotating theat least one cam. The motor can be located anywhere within raiser seat,and may be contained in a separate detachable casing. For example, itcan be side-by-side, above or below the cam, or contained within theseat unit. The motor may drive the cam directly or indirectly. With anindirect drive various drive transfer components can be used, includingdrive couplings and meshed gears. If the motor drives the camindirectly, the power transfer components can be chosen to allow thedrive to be transferred from wherever the motor is located. Furthermorethe drive transfer components can be also be chosen to alter thecharacteristics of the mechanism, for example the torque or rotationalspeed. The motor can be controlled via a control box for all requiredoperational parameters.

Preferably, the at least one cam is attached to a coaxial gear in meshedengagement with a rack such that translation of the rack results inrotation of the at least one cam.

Preferably, the rack is driven by a gear powered by a motor.

Preferably, the profile of the at least one cam is chosen dependent onthe path followed by the seat as it moves between the first and secondposition. This allows the motion of the seat to be tailored to specificpurposes by the choice of cam profile. Thus, for example, thecombination of lift, tilt and cycle time/speed of operation of the seatcan be varied as required for a particular application. Alternatively, aset of predetermined cams and/or control programs can be provided givinga range of common movement profiles.

Preferably, the movement mechanism further comprises at least oneactuator fixed at a first end to the seat. In one embodiment a secondend of the actuator is fixed to either the seat frame or the seat unit,and the second end can move relative to the first end in a generallyvertical direction. An actuator is a simple way of achievingtranslation. In some circumstances, part or all of the seat may berequired to mostly translate in a single direction. A combination of theleast one cam with the at least one actuator is a simple way to achievethis motion. A further advantage is that the overall operating range andcapability of the at least one cam can be maximised.

Preferably, the at least one actuator comprises at least one threadedmember in meshed engagement with at least one gear driven by a motor.The at least one actuator can also be a lead screw. Reinforcing elementscan be located in a housing for the at least one actuator.

The seat and/or seat unit can include an aperture. The seat can then beused as a commode. In one embodiment, the seat and/or seat unit are notpermanently attached to the seat frame. Preferably, the seat frameand/or the seat unit can then include a removably attached soilsreceptacle to sheath and enable easy emptying of the commode. The soilsreceptacle can have a cover to enable clean usage of the seat and reducerisk of contamination further by offering the sheath facility for one ormore of the frame, seat unit and user environment with soils.

Preferably, the seat frame is mounted on wheels or sliders. This allowsmovement of the seat from one location to another, and allows use of theseat as, for example, a wheelchair, or alternatively to move the seat towhere it is required to be used.

Preferably, when the seat frame is mounted on wheels, the raiser seatcan further comprise a brake system. The brake system can be operativeto prevent motion of the wheels during a lifting or lowering operationof the seat, or any other use which requires the seat to be held stablewithout moving, or any other use that requires the seat/frame. This canimprove the safety in use of the seat.

Preferably, the brake system is associated with the movement mechanism,such that operation of the movement mechanism causes the brake system toact to prevent rotation of the wheels. This can provide a further safetyadvantage, by ensuring that when the movement mechanism is operated, thebrake system is automatically applied.

Preferably, the at least one cam either incorporates a friction reducingcoating or is manufactured at least partially from a friction reducingmaterial. In embodiment, the whole of the at least one cam ismanufactured from a friction reducing material.

Preferably, the at least one cam is linked to the seat in a way whichdoes not significantly alter the load on the movement mechanism.

In one embodiment, this is achieved by the use of a fixed connectingmember (or protrusion) extending from the at least one cam. Preferablythe connecting member is an extension of roller shafts of the at leastone cam. The connecting member can locate within a corresponding slot inthe seat and act to support the seat on the at least one cam. It canalso prevent the seat from moving away from the at least one cam withoutsignificantly altering the load on the movement mechanism.

In an alternate embodiment, at least one single or double actionpneumatic or hydraulic cylinder can connect the at least one cam and theseat. The cylinder can feature an orifice with dimensions chosen so asto avoid placing any further loads on the movement mechanism, yet givesufficient resistive load to prevent the seat moving away from the cam.In the event that a load is placed on the seat such that it becomesdetached from the cam profile edge, the fluid within the cylinder willbegin to exit the orifice at a higher rate and thus place a resistiveload on the seat's movement away from the cam profile edge.

The resistive load will continue to be applied until the seat movessufficiently far that the pneumatic cylinder is extended to the limit ofits stroke, or the load case is reversed and the seat regains contactwith the cam.

Preferably, the at least one cam comprises at least one of the followingfeatures: an integral gear; an integral shaft; an integral bearing; anintegral bearing surface; an integral roller; a one roller assembly; atleast one connection member; a roller carriage; an integrated rollercarriage in whole or in part; an integral roller track; an integralseal; integral sealing surfaces or sealing area; an at least oneintegral location and retention component; a blade; a shaft recess; abearing recess; a protrusion recess; an externally threaded member; aninternally threaded member; one hole; one roller type or plainbearing/bush; one press fit member; one threaded member; one taper edgeprofile; one alternative edge profile; one increased thickness sectionthat can run the full length of the cam; and multiple blades

More preferably, in the event that the cam comprises more than oneblade, the integral location and retention component can be an area ateither side of a main cam and/or the integral gear can have a differentdiameter, size, form or shape from that of other sections of the camshaft.

Preferably the seat comprises a guide track adapted to receive theconnecting member. In one embodiment the guide track comprises a lineartrack located at the side of the seat in a position where the seat issupported by the at least one cam. In another embodiment, the seat canfurther comprise at least one thickened material section, roller, abearing, a friction-reducing coating, or a friction reducing material,positioned along the part of the seat which is in contact with the atleast one cam. If at least one roller or bearing is used, the track canbe mounted on the at least one roller or bearing.

Preferably, the seat unit is removably attached to the seat frame. Theattachment mechanism can include connections for electrical circuitry.These connections can be encapsulated within the seat frame. Theconnections can be for power, sensors, control or other functions.

Preferably, the seat frame comprises handles. The handles can be placedat various locations to allow for safe interaction with the user oroperator, and allow for controlled and safe movement and location withother components and assemblies.

Preferably, the seat frame comprises footrests.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of exampleonly with reference to the accompanying drawings, in which:

FIG. 1 depicts a perspective view of a first exemplary embodiment of thepresent invention;

FIG. 2 depicts a plan view of the seat of a first exemplary embodimentof the present invention, cut away to show the movement mechanism inplan view;

FIG. 3 depicts a more detailed view of one half of the movementmechanism shown in FIG. 2;

FIG. 4 depicts possible battery, control box and motor positions in afirst exemplary embodiment of the invention;

FIG. 5A depicts side a view of the seat used in a first exemplaryembodiment of the invention;

FIG. 5B; depicts a front view of one side of the seat depicted in FIG.5;

FIG. 6 is a side view of the movement mechanism of a first exemplaryembodiment of the present invention;

FIGS. 7A and 7B depict a cross sectional view of the movement mechanismdepicted in FIG. 6, showing the guide track provided on the seat in afirst embodiment;

FIG. 8 depicts a plan view of the cam mechanism of a first exemplaryembodiment;

FIG. 9A depicts a plan view of the cam depicted in FIG. 8;

FIG. 9B depicts a dual axis sprung cam;

FIG. 10 is a side view of a cam profile for use with a first exemplaryembodiment of the present invention;

FIG. 11 depicts a cross section of the cam depicted in FIG. 9;

FIGS. 12A to 12J illustrate various positions in the motion of a seatfrom the lowered to a partially raised position according to a firstexemplary embodiment of the present invention;

FIGS. 13A to 13C depict a second exemplary embodiment of a liftingsequence;

FIGS. 14A, 14B and 14C respectively depict a side view and plan view ofa cam movement mechanism and an overall plan view according to a thirdexemplary embodiment;

FIGS. 15A, 15B and 15C respectively depict a side view and plan view ofa cam movement mechanism and an overall plan view according to a fourthexemplary embodiment;

FIG. 16 depicts a cam and track mechanism of a fifth exemplaryembodiment;

FIG. 17 depicts one side pod assembly of a sixth exemplary embodiment ofthe present invention;

FIG. 18 depicts a cam lift mechanism for use in the embodiment of FIG.17;

FIG. 19 depicts a front view of the top of an embodiment using the sidepod assembly of FIG. 17;

FIG. 20 illustrates the retractable wheel mechanism in for use in theembodiment of FIG. 19;

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a side view of a first embodiment of a complete raiserseat 2 according to a first exemplary embodiment of the presentinvention. The raiser seat 2 has a seat 10 which forms part of a seatunit 12. A seat frame 4 includes a back rest 6 and arms 8. The seat 10and seat unit 12 are supported by the seat frame 4.

The back rest 6 can tilt, either by its manufacture from an appropriateflexible material, or through the provision of a pivot point or viaconnection to a further pivoting joint component or assembly.

Movement of the chair is assisted by wheels 14 located on the bottomcorners of the seat frame. The seat frame can include handles that canbe located at any point on the seat frame, to allow for safeinteractions with the user, interaction with operators and users foraccurate controlled movement and location with other components andassemblies.

The mechanism by which the seat 10 is raised and lowered will now beexplained. FIG. 2 shows a plan view of the seat 10 with the liftingmechanism below it. FIG. 3 shows a close up of one half of the liftingmechanism shown in FIG. 2.

As shown in FIGS. 2 and 3, the seat 10 and the seat unit 12 include anaperture 102 to allow its use as a commode.

FIGS. 6 and 7 depicts a side view and a cross section, respectively, ofthe lifting mechanism. A front mounted lifting mechanism 112 is locatedeither side of the aperture 102 and comprises two main actuator parts112 on each side as can be seen in FIG. 7B. The actuator 112 ispivotally attached towards the front of the seat 10. This allowsmovement of the front of the seat 10 in a generally vertical direction.At least one cam 104 supports the seat 10 further towards the rear thanthe actuator 112. Rotation of the cam 104 causes vertical movementand/or tilting of the seat 10 depending on the relative movement of thepoint of contact between the seat 10 and the cam 104 and the pivotalconnection to the actuator 112.

The actuator 112 is threaded. In this embodiment a lead screw 120 isused internally to the actuator and is moved by rotation of a gear 114.The gear 114 is meshed with a gear 110 which is powered by an electricmotor in this embodiment, although other types of power source are alsopossible.

As shown in FIG. 4, the power source for the motor can be located atvarious locations, and preferably at the locations denoted 300 and 306.Likewise, the control box can also be located at various locations, andpreferably at the locations denoted by 304 and 300. In FIG. 4, referencenumeral 105 serves to demonstrate the boundary of the seat unit.

The control box, any sensory equipment and the battery are connected tothe motors in the mechanism by any suitable means, such as a removablecable or a fixed cable. This applies no matter what their location is,whether in close proximity 304, 306 to the movement mechanism, at alarger distance, or external to the seat unit 12, suitable connectioncan always be provided by appropriate means.

FIGS. 5A and 5B show the main features of the seat 10 in thisembodiment. The seat 10 comprises features which can either be separatecomponents that are fixed to the seat or integrated in whole or in partin the manufacturing process. In this embodiment this is particularlytrue of the guide track 800 which receives a connecting member 124 (orprotrusion) attached to the cam 104. This allows the safe use of camswith no load increase on the mechanisms; this system allows the seat toeffectively float on the cam whilst incurring little, if any, mechanicallosses.

A pivot point 802 allows for removable attachment of the actuator 112suitable for lift and pivot operations associated with seat movement asillustrated in FIG. 12A-12 J, which is described in more detail later.Other types of actuator than the actuator 112 with lead screw 120 mayalso be used.

The removable attachment is achieved in this embodiment by an assembly808 comprising a plain shaft with an internal or external threadedsection that interfaces with a second member with an internal orexternal threaded section. Other components can also be used in thisassembly. These include plain washers, washers that exertcircumferential force under load, self locking internally threadedmembers, and members that exhibit radial force exertion for position andinteractive stability. These components can have inner diameters belowthe outer diameter of the plain shaft, an outer diameter in excess ofthe plain shaft and be fitted in a groove or undercut to the plainshaft.

The function of assembly of 808 can also be provided by members whichexhibit an interference relationship to form a permanent connection.

A seat track 810 is provided at the point at which the edge profile ofthe cam 104 contacts with the seat. This can be formed as an integralpart of the seat at manufacture. The seat track 810 will preferablyconsist of a thickened material section manufactured in the samematerial as the seat. Alternatively it can be manufactured at the sametime as the seat in whole or in part of a friction reduction material.The track can also be coated after the original source manufacturingprocess with a friction reducing coating.

A number of possible alternate constructions of the seat track will nowbe described. The seat track can consist of rollers and/or linear slidesand/or track rollers and/or wheels and/or castors. If rollers and/orwheels and/or casters are used, they will be either permanently attachedor removably attached to the seat over the given length of the cam/seatinteraction (see for example that depicted by FIGS. 12A-12J anddescribed in more detail below) and spaced such that the resultantaction of the seat is smooth and with no undulation. If linear slidesare used, preferably at least one will be used at each cam/seatinterface. The linear slides will be attached to the seat via threadedor interference members such that the smooth and reduced frictionparameters of the linear slide system are exploited.

In another alternate construction of the seat track, the predefinedroller system includes the addition of a flexible or rigid, continuousor unconscious track that can be either captivated or non-captivated andis situated between the rollers and the cam 104. The track is such thatthe distance between each roller for smooth seat tilt and lift can beincreased over that of a system using pure rollers. The increase inpermissible roller pitch is such that fewer rollers are used and withthe interaction of the track, there is little detriment to thesmoothness of seat operation. The seat track can be profiled to suit theprofile of the cam and aid in smooth, safe operation with reducedmechanism load friction characteristics. Combinations of these seattrack constructions can also be utilised.

Returning to the description of the movement mechanism, the pivot andlifting of the seat is taken around the point 802. The pivot and liftassembly 808 is of sufficient strength to withstand the loads generatedby operation of the raiser seat 2 in predetermined limits. The assembly808 may include a plain or roller type bearing and/or a frictionreducing coating and/or be manufactured from a friction reducingmaterial. The assembly 808 is housed within a structurally sufficient,integrated and/or fixed member. The member can be integrated atmanufacture with the same or a different material. The material can havefriction reducing properties and structural capabilities or juststructural capabilities, providing it can retain the connection memberof the actuator sufficiently in all planes except that of the requiredrotation around the pivot point axis.

The member housing the assembly cane be a separate component which isfixed to the seat via welding and/or bonding and/or a mechanicalfastening and/or a slider and/or and interference fit. In that case, thefits need to be suitable for all the required usage of the productduring the operation of the unit.

FIG. 6 shows the preferred cam mechanism, which in this embodiment isdriven by an electric motor. The cam 104 has a gear 106 coaxiallyremovably or permanently attached to it, either so that the gear 106 andthe cam 104 share a common axis of rotation and rotation of the gearresults in rotation of the cam. This gear is then driven by a toothedrack. The toothed rack is itself driven by the operation of a lead screwor worm drive connected/meshed with a gear connected or meshed to anelectric motor.

FIGS. 6 and 7 also depict more detail of the actuator. It can beobserved that the actuator 112 is preferably a casing in which a leadscrew 120 removably or permanently captivated. The lead screw operatesvia removably or permanent connection to a gear 114 meshing with gear108 which is driven by the electric motor 107. The whole assembly islocated on bearings or friction reduction material that both holds theunits securely whilst allowing rotation with minimum friction. Thebearings can be roller type bearings where cylindrical or sphericalcomponents are utilised and/or plain bearings and/or have frictionreduction coatings.

In FIG. 7 the connection members of the actuator system are show. A topconnection member 118 is provided which can be removably or permanentlyattached to the seat pivot assembly 808 in such away as to allow thepivot action of the seat. In this embodiment the end is tapered to makesure that no encroachment on the seat occurs at any point during theoperating cycle of the mechanism. The lead screw 120 is held captivewithin a casing.

The lead screw 120 has sufficient thread characteristics to achieve thedesired performance of the complete unit. The lead screw 120 comprisesan externally or internally threaded bar and engages with an internallyor externally threaded seat or main bar connection member 118. The twomembers exhibit meshing thread patterns.

The connection member 118 is of hollow cylindrical form with a threadedsection or with a complete threaded length from an open end. The openend is the opposite end to the seat connection end. The thread of thelead screw 120 can mesh with the threaded section of the connectionmember 118 and when rotation is applied to the lead screw the connectionmember 118 thread advances or retracts along the length of the leadscrew 120. The lead screw 120 is able to enter the hollow section of theconnection member 118 to a depth equal or above that of the overallrequired stroke. Lubrication can be added to the system to ensurefriction reduced running and higher mechanism efficiency.

FIG. 7 also depicts a cross-section through the seat portion 12 and theseat 10 to reveal the inner workings of the movement mechanism and theinteraction between the seat guide track 800, the cam and the connectionmember 124. In this embodiment the seat is securely linked to the camvia a connection member 124. This securely retains the seat to the camto allow temporary breaks or permanent connection of the cam profile,whether it be roller, bearings, tracks, wheels, casters or any othersuch profile interface and a track formed on the seat. It thereforeenables the temporary or permanent connection of the seat to the cam (aplan view can be seen in FIG. 4).

In this embodiment the seat is secured on the cam by the interfacebetween a connection member 124 at the end of the cam and at least oneguide track formed on the seat. This allows relative movement betweenthe end of the cam and the seat, and ensures that the seat is notaccidentally disengaged or otherwise removed from the cam. It has afurther advantage of not yielding any further mechanism load during alifting operation. The connection member 124 is such that the seateffectively just rests on the cam and hence the retention of the seat onthe cam is achieved with little or no mechanical loss.

The clearest view of the cam mechanism can be observed in FIG. 8, whichdepicts a plan view. The cam exhibits a wider member at the rear of thecam blade. This wide member houses the rollers and the connection member124.

In this embodiment the connection member 124 forms an extension of oneof the roller shafts of the cam blade. The connection member 124preferably fits into the cam via an inference entrance into the camshaft, into a recess sufficient to allow reduced friction usage.

The roller is of sufficient diameter and width to allow for effectiveoperation. A number of alternate constructions of the roller can beused. Preferably, the roller consists of an outer diameter materialwhich is located on a roller type or plain bearing. This is responsiblefor mating with the seat track. Thus, the position of the bearing axialpivot point in relation to the axial pivot point of the at least one camforms the effective profile of the at least one cam. The bearing is inturn located on a shaft, the shaft may include an extended section suchto allow connection with the seat guide track.

In an alternate construction of the roller, the outer diameter materialmay not be present, in that case the roller is than a roller type orplain bearing which is directly responsible for mating with the seattrack. Thus, the position of the bearing axial pivot point in relationto the axial pivot point of the cam forms the effective profile of thecam. The bearing is in turn located on a shaft, the shaft may include anextended section to allow connection with the seat guide track.

In another alternate construction of the roller, the roller isintegrated with the shaft which is responsible for mating with the seattrack. Thus, the position of the roller axial pivot point in relation tothe axial pivot point of the cam forms the effective profile of the cam.This integral roller/shaft format relies on the cam to providesufficient friction reduction housing to ensure effective operation. Aswith other constructions of the roller, the integrated roller shaft mayinclude an extended section which allows connection with the seat guidetrack.

The preferred roller housing section of the cam is preferably indicatedby the increased wall section of the cam blade. This section can be madefrom a material different to that of the main cam and is preferablyintegrated at source/route manufacturing process.

To aid the effective rotation of the roller, preferably an increasedwall thickness section integrated with the at least one cam can bemanufactured in whole or in part from friction reduction material and/orcan house roller type or plain bearings in the recesses for the rollersshafts to locate within. In this embodiment bearings of either type arepreferably fitted first, then the roller is aligned with the centres ofthe bearings, the shaft is then located through the centres of thebearings and rollers. The bearings have an interference fit with the camand the shaft has an interference fit with both the bearings and the atleast one roller.

The shafts and bearings are such that they would be able to retainedfurther once in position. For the shaft and bearings, this can beachieved by using further press and interference fit members andthreaded sections, with plain washers or those that exert acircumferential force when under load; self locking internally threadedmembers; and members that exhibit an inner diameter below the outerdiameter of the plain shaft and an outer diameter in excess of the outerdiameter of plain shaft. They can be used in relation to their radialforce exertion for position and interactive stability and fitted in agroove or undercut to the plain shaft.

In an alternate construction, the at least one roller and shaft arefitted to the at least cam blade via a recess as referenced previously.The shaft is seated within a recessed area, the recessed area comprisingan integrated at manufacture or post-manufacture plain bearing. Theplain bearing is made of material sufficient to withstand the loadingand service requirements and yield reduced friction operation.

In another alternate construction the roller and/or bearing, with orwithout an outer of different or the same material is located on the camblade 150 via a protrusion integrated with and stemming from the camblade 150. The protrusion forms form an integral shaft on which to placethe roller and/or roller type or plain bearing. In the case of theroller type or plain bearing the fit would preferably be that of aninterference fit that may include bonding agent and other mechanicalretention methods such as threaded members, threaded and locking membersand members that exhibit inner diameters below the outer diameter of theplain shaft and an outer diameter in excess of the plain shaft and usedin relation to their radial force exertion for position and interactivestability and fitted in a groove or undercut to the plain shaft. In thiscase the roller type bearing or plain bearing could be retained via apress fit component.

In other constructions the at least one protrusion allows for the rollerwith a plain type bearing to be securely fixed within to form a newroller internal diameter that corresponds to that of the inserted plainbearing, or an integrated at source of manufacture plain type bearing.In both cases the bearing will preferably be of a material with frictionreducing properties or the at least one protrusion itself will consistof material that of friction reducing properties and structural rigiditysuitable for purpose and which can be integrated with the cam blade 150at the source of manufacture or such that the plain bearing can be fixedto the protrusion. In all cases the roller is preferably secured to theprotrusion by an interference fit that may include bonding agent andother mechanical retention methods. such as threaded members, threadedand locking members and members that exhibit inner diameters below theouter diameter of the plain shaft and an outer diameter in excess of theouter diameter of the plain shaft and used in relation to their radialforce exertion for position and interactive stability and fitted in agroove or undercut to the plain shaft and or further members retainedvia a press fit to the at least one protrusion.

In all the constructions describing at least one roller and/or bearing,protrusions and or recesses, it is known that the multiple examples canbe utilised on the at least one cam blade present on the at least onecam. Those multiple examples can be distributed across the length of theat least one blade and/or the at least one cam at points relative to theaxial rotational point of the at least one cam and thus the at least oneprofile can be achieved.

In an alternate construction of the cam, the at least one cam can havemultiple blades. Located between the blades is either a continuous shaftthat runs between the blades, or two non continuous shafts located as aprotrusion on each blade. The preferred format is that of two blades,the description of which can also be applied to any additional blades.

This alternate construction can be manufactured in one piece as acompletely integral member or in several sub sections that are laterjoined. The joining process can be completed via welding, interferencefit between protrusions and corresponding recesses on each part, and/ormore traditional mechanical means. This includes employment ofmechanical retention methods such as threaded members, threaded andlocking members and members that exhibit inner diameters below the outerdiameter of the plain shaft and an outer diameter in excess of the plainshaft and used in relation to their radial force exertion for positionand interactive stability and fitted in a groove or undercut to theplain shaft and or further members retained via a press fit.

In the case of integrated manufacture, the roller can be placed betweenthe blades and aligned to correspond with at least one hole centre ineach of the blades. It is preferred that a shaft is then pressed throughthe assembly via the holes in the blades with an interference fitthereby created between the at least one shaft and the at least one holein each blade.

Roller type or plain bearings can be located in the hole in the camblade such that friction reduction is present in the system. In thisembodiment an interference fit is created between the roller and theshaft at the shaft pressing in a similar manner to that of theabove-described blade/shaft interactions.

In the case that bearings in the cam blades are incorporated, the rollerpreferably has an interference fit with the shaft. The roller canfeature at least one integral roller type or plain bearing. In that casepreferably no bearings are present in the cam blade. Instead the shaftwould be preferably retained by the cam blades

When multiple cam blades are used, at least one of the blades canfeature a shaft that is sufficient in length to produce a continuouslength between blades.

In any embodiment or construction, the protrusions can be distributed atany point across the cam blade. The protrusions on the cam aresufficient to allow location of the integrated roller and roller typeand/or plain bearings that will be used to set the effective profile ofthe cam. In this embodiment the roller type or plain bearings will beeither removably or permanently attached to the roller, or in the plainbearing integrated at manufacture and of suitable friction reducingmaterial. The suitable friction reducing material can be different tothe bearing.

In one construction a carriage unit is located on at least one cam bladeor between multiple blades preferably at any point over the surface ofthe cam blade. The carriage allows mounting of at least one shaft,roller and roller type and or plain bearings. The roller can be mountedsuch that it has free rotation and part of its circumference is abovethe carriage unit. The carriage can either be fixed or retain theability to freely rotate.

Multiple roller assemblies and or roller carriages can be located acrossthe cam blade or between at least two cam blades. The rollers are setrelative to the axial rotation centre of the cam and preferably set theeffective profile. A continuous or non continuous covering can be placedover at least one roller (preferably two) to form a track or covering.

The track or covering can be rigid or flexible and held moveably captiveor non-captive with the confines of the cam and roller integrated body.The track or covering is located between the cam roller and the seattrack such that, when the seat cam starts to rotate, the track orcovering moves relative to the interaction of the cam rollers andmovement of the seat.

The benefits to this system are fewer cam rollers 122, 126 are requiredfor undulation free operation of the seat. Furthermore all cam rollersare able to produce relatively equal wear characteristics.

The carriage, continuous or non continuous shafts, rollers, bearings(roller type and or plain) and cam blade can be securely retained,preferably by interference fit between shafts and corresponding recessesor holes on each part. More traditional mechanical means can also beused via employment mechanical retention methods such as threadedmembers, threaded and locking members and members that exhibit a innerdiameters below the outer diameter of the plain shaft and an outerdiameter in excess of the plain shaft and used in relation to theirradial force exertion for position and interactive stability and fittedin a groove or undercut to the plain shaft and or further membersretained via a press fit, with the rollers having free rotation.

The roller assembly is positioned such that no undulation is caused tothe seat during lifting or any other operation. A roller assembly caninclude at least one roller type or plain bearing, at least one rollerand at least one shaft.

The thick section associated with the housing of the rollers cancontinue down the full length of the cam blade or stop at any pointalong its length. Alternatively, no thick section could be used.

The cam can be made from laminate or differing materials that combineproperties of strength and friction reduction such as a metallic coresurrounded by a polymer outer surface.

The roller can either rotate about the bearing relative to the shaft orthe roller and bearing can rotate about the shaft.

The roller and/or the bearing, whether plain or roller type are set suchthat the outer surface or outer diameter is positioned above the camand/or at least one cam blade.

The roller can be removably attached or permanently attached.

If a roller type of plain bearing is used, it can be removably attachedor permanently attached to the cam and/or the cam blade.

The shaft can be removably attached or permanently attached to the camand/or the cam blade.

The cam and cam blade can be removably attached or permanently attachedto the cam and/or the cam blade.

The roller carriage can be removably attached or permanently attached tothe cam and/or the cam blade.

The cam can be any shape or form, which is operative to produce the liftprofile desired.

FIG. 8 also demonstrates the other parts of the system. An electricmotor and reduction gear box 128 is preferably removably attached orpermanently attached directly to a drive coupling 130. It is preferredthat the motor and reduction gear box axe integrated; however, the unitscan be separate and joined via means of a shaft and retained viamechanical means such as a keyed shaft and key receiver and/or threaded,bonded or interference members.

In an alternate construction, no drive for the coupling is used.Instead, the motor directly connects removably or permanently to a gearthat meshes with the gear before removably or permanently connecting to,and driving, the remaining mechanism.

In this construction the motor/drive coupling is preferably made via akeyed and grub screw fit. Preferably an alternatively connection can bemade via use of a keyed and bonded fit. The coupling can take anymisalignment out of the system and ensures that minimal non axial loadis transmitted to either the lead screw 140 or the motor 128.

The drive coupling is removably attached and or permanently attached tothe lead screw 140. The coupling and the lead screw are keyed to suit,with further retention of the joint via bonding agent and/or a grubscrew.

Between the coupling and the integrated drive nut, it is preferred thatthe bearing support surface is located. It is preferred that the bearingsupport surface takes either roller type or plain bearings. In thisembodiment plain bearings 132, 134 are used. This description alsoapplies to the lead screw cam end support 140. The lead screw bearingsurface as with any other lead screw surface can be coated preferablywith friction reduction coatings to ensure smooth increased efficiencyoperation.

The lead screw is meshed with the integrated drive rack nut 136. Thedrive rack nut has a corresponding thread pitch to that of the leadscrew. In this embodiment the pitch of the thread falls between 0.25 mmand 5 mm; however, other thread pitches can used dependent on the systemrequirements.

The integrated drive rack unit features a threaded section that mesheswith the lead screw and the toothed rack section that integrates withthe integrated cam gear. The nut 136 is preferably made in one completesection with little or no post route manufacturing process work beingrequired.

It is preferable the thread section of the nut is made from a differentmaterial to that of the lead screw, with the threaded part of the nutbeing the threaded insert into the main body of the nut. The insert willbe removably or permanently attached to the nut body such that it doesnot move relative to the main nut body while in operation.

Preferably the threaded nut insert is a different, preferably softermaterial to that of the lead screw. The nut main body and the toothedrack 136 a are able to be manufactured from the same material as leadscrew. It is preferred this be either a metallic of polymer basedmaterial; however, other materials can also be used.

It is preferred that the drive rack nut is cast or injection moulded.The unit can be handed and/or universal. By this, it is meant that therack section can be a feature on the nut main body both to right and/orto the left of the nut and thus fall either side, or at both sides, ofthe lead screw.

As can be observed from FIG. 7, is preferably located such that itremains in contact directly or indirectly with an internal surface ofthe seat portion 12. This stops the toothed rack 136 a being able tobecome disassociated from the integrated cam drive gear. Furthermore thedrive rack nut, and in particular the toothed rack section, ispreferably either a circular, oval or square form; however, other formscan also be used.

The rack section of the drive rack nut 136 is connected to the cam drivegear via the integrated toothed section 136 a which meshes with the camdrive gear. The cam is held in place preferably via an integral camshaft on which roller type or integrated plain bearings are removably orpermanently located; these will be discussed later in more detail.

The preferably integrated bearing also houses an integral retentionsurface to retain the at least one cam in a fixed position relative toother mechanism components whilst not limiting the rotationcharacteristics.

The mechanism is activated by the connection of the motor to the powersource and preferably via an electronic control box. The control boxissues an instruction from an external source of correct protocol to themotor in terms of speed and rotational direction. Integrated sensors canalso influence the control box function and thus instruction set givento the motors.

The motor then drives the integrated gear box, which in turn drives thecoupling 130 causing the coupling to rotate. The coupling rotationcauses the lead screw to rotate, which in turn drives the drive nutwhich travels linearly across the lead screw. This motion drives thetooth rack section, which drives the integrated cam gear, which thenrotates the cam around an axial pivot point to lift or lower the cam.Thus, the seat is raised and/or tilted in either direction.

The components of the raiser seat are preferably made from non-magneticmaterials.

The seat 10 can rest on the interface between a projection at the end ofthe cam when the seat is in a lowered or horizontal position. The seatcan also rest upon the seat unit and both provide a solid support to theseat when it is not being raised or lowered. A plan view showing onlyparts of the cam mechanism is depicted in FIG. 8.

A protrusion 124 is provided on the end of the cam, together withrollers 122, 126 which support the seat and allow relative movement ofthe contact point between the cam and the seat.

An example profile of the cam 104 is illustrated in FIG. 6. A plan viewis shown in FIG. 9. This example profile includes recesses 148 intowhich a projection to engage with the at least one guide track on theseat can be mounted. FIG. 11 shows a cross section through oneembodiment of the body of the cam.

As is shown in FIGS. 9, 10 and 11, a variety of features can beintegrated with the cams. In particular the cam can include anintegrated gear, at least one roller or plain bearing/bush, shaft andshaft locators. In alternate embodiments, some or all of the integratedfeatures can be included. The cam can be manufactured from differentmaterials at different locations from the one source route ofmanufacture. The cam can have a composite materials structure and/orlaminate and/or a central core of a metallic material, with an outsurface of a polymer based material. It is preferred that the surfacessuch as the cam shaft and attachments 144 and 146 are integral fromsource manufacture and are of a material that can differ from the maincam material. They are preferably manufactured from a friction reducingmaterial and all surfaces of the cam can be coated in a frictionreducing coating.

The at least one cam has a removably and permanently attached integraldrive gear that preferably is of a diameter between 5 mm and 200 mmpitch circle diameter and a metric modular teeth size of between 0.25MOD and 6 MOD. It can be noted that all other meshing gears, includingthe toothed rack, will exhibit the same modulus and preferably be eitheranti-backlash or spur or helical format. Gears in the system can differin format, however, all meshing gears will be the same format.

An example of the raising motion of the seat in this embodiment will nowbe described with reference to FIGS. 12 a to 12 j. FIG. 12 a representsa lowered position of the seat and FIG. 12 j represents a partiallyraised position of the at least one seat. The first sequence of themotion consists entirely of lift and is illustrated from FIGS. 12 a to12 d. During this phase, the cam 104 rotates such that the rear of theseat which is supported on the cam 104 (or rollers 126, 127 or othermembers as has been previously described) rises at exactly the same rateas the actuator 112 is extended. This results in a pure lift of theseat.

The next stage of the procedure tilts the seat. The actuator 112 ispreferably stopped automatically by the control unit but the cam 104continues to rotate. This results in movement of the rear of the seatrelative to the front which is held in position by its connection to theat least one actuator 122. Thus, as can be seen from FIGS. 12 e to 12 jthe tilt of the seat becomes progressively greater. This combination oflift and tilt has been found to be particularly advantageous inassisting a person from a sitting to a standing position.

The lift profile can be altered by changing the profile of the cam, forexample for one in which the seat is supported closer to the cam pivotpoint in the lower position, or one in which the pivot is locatedfurther from the cam pivot point in the lower position. Interchangingthe cams can produce a wide range of differing move profiles dependingon what is required. The precise lift profile will depend on therequirements of the user; the total overall time of the lifting cycle(the tilt and lift speed as well as other resultant movements) can alsobe adjusted allowing customisation of the mechanism to all userrequirements.

From FIGS. 9 a and 9B, in a further construction, the cam and/or camblade 150 can rotate around the centre line at any place where a pivotis located. The cam/cam blade can have multiple rotation points and thusgive the cam many degrees of freedom. The multiple or single rotatingsection allows the roller and/or roller assembly and or shaft assemblyto be kept flush with the seat track at all times, even when the seatbegins to roll and or pitch.

This dual rotating split axes cam has each section 150 a, sprung loaded152 or 162, or 160 (160 is a complete motion resilient coating) andpivots around its centreline 164 and protrusion 156; the protrusion orthe cut out in which it sits can achieve the desired rotation via rollertype and or plain bearings being insert onto or into the respectprotrusion or cut out.

In this construction, the sections can be held in place via interferencefit and or wires of other such structurally sound and or flexible meanscan retain the section; the “wires” 166 can run the whole section and besecured at both ends of the cam such that they provide the required wiretension and thus required flexibility. The wires are preferablymetallic, polymer based and/or rubber based.

The other method is to employ a centre shaft, indicated by 168, with endstop section 170, preferable the shaft 168 is an integral part of thecam (although it can be a separate section) and section 170 is aseparate section, or 170 and 168 can be integral and then later joinedto the cam. It is also possible for the end section to be used to mountfurther non-rotation cam sections and thus form a two or multipartrigid/flexible cam. This is true of all flex solution as described. Inthe case of 168 the block closest to the integral gear does not rotate,this is the anchoring block. All fixings are as has been described i.e.interference fits, mechanical fits, threaded members(internal/external), press fittings, rivets (which can be applied in anyembodiment) and any other method mentioned; all the sections can beplace on the centre shaft, the shaft could be one long roller type orplain bearing and or coated with friction reducing materials such thateach section is able to free rotate or each section/block can house aroller type or plain bearing or have integral bearing material on itsinner bore surface.

The roller and/or roller assembly and/or shaftassembly/protrusion/connection and/or carriage unit members be attachedto the sections 150 a as has previously been described and thus can takeany profile that allows the unit to effective remain in contact with theseat track through all aspects of the seat displacement.

All the roller and/or roller assembly and or shaft assembly, can bemounted in either the at least one cam and/or cam blade and/or seatand/or carriage unit with the use of spring loaded assemblies eitherthose mounted internally via cavities/slots and pegs 152 a, 152 and 154and/or those mounted externally such as 162 which are can be applied assingular flexible strips and/or multiple and at any point and orcombination over each joint and or a complete flexible sheath 160 thatallows all the required connections i.e. the at least one roller and/orroller assembly and/or shaft assembly/protrusion/connection and/orcarriage unit without exception.

In a further construction the drive system can feature alternative gearsand these can include worm drives, spur, helical, bevel, anti-backlashtype gears can be present and or combinations where possible.

In all constructions, the roller and/or roller assembly and or shaftassembly can preferably feature convex or concave (positive or negativebowing and or camber) and raised sections or any other shape/profile inbetween and thus are able to cope with any contact scenario.

A second embodiment of the lifting mechanism is depicted in FIGS. 13A,13B and 13C. In this embodiment two pairs of cams 202, 204 (whichexhibit all the same characteristics and features as 104) control thelift and tilt of the seat 206 (which exhibits all the same features as10). The similarities of the systems in terms of mechanisms are alsoapparent from FIGS. 14A, 14B, 15A and 15B.

The pair of cams 202 towards the front of the seat is pivotallyconnected to a projection 208 formed on the seat 206 at certainpredetermined points in the lifting cycle. The pair of cams 204 supportsthe rear of the seat directly by a slider, track or roller mechanism 210as previously described in other embodiments. A further slider, track orroller mechanism 212 as previously described in other embodiments,supports the front portion of the seat 206, above the pivotalconnection. This allows the contact position of the seat 206 and the cam202 to move, while still entering, existing and maintaining the seatedlocation with the pivotal connection.

The pivotal connection via projection 208 is achieved by the means of arecess which is open at one end. The positioning of the recess is suchthat the seat is has a pivot point on which the rear cams can act andthus tilt the seat.

The front and rear cams exhibit all the same characteristics asdiscussed above in relation to FIGS. 2-12J. This quad cam embodiment isa true “floating” seat cam mechanism. It is both safe in use and retainsthe seat on the cam with little or no mechanical losses.

The cams have the same roller assemblies 122, 126, the same removablyattached and or permanent gear 106. Furthermore the connecting member124 is also present on all of the cams. With relation to the seat allthe main features are present, this includes the at least two seat guidetrack 800 and 804 and seat guide track 810. The component referenced as208 acts in similar ways to 802, with the protrusion 202 being a furtherembodiment of the parameters of the connecting member associated with124. All these have previously been described in the text and with theirassociated components and members are applicable to this embodiment.

In a lifting sequence, the front cams rotate in the opposite directionto those of the rear units and thus they advance towards each other. Asthe front cams rotate with the aid of roller assemblies and slides (aspreviously described), at a predetermined point they interact with apivotal connection. The movement up to that point is preferably purevertical lift. However combinations of movement can be introduced toalter the seat displacement and the point at which the cam engages thewith the pivotal connection.

The seat 206 preferably rests on the cam rollers 122 and 126 aspreviously discussed. Each of the cams front and rear preferably engageswith its own seat guide track. However, the seat guide tracks can beadapted to run a length suitable for the requirements of each side, thisallows one front cam and one rear cam to use the same guide track.

Each of the four cams has the connection member 124 in the same manneras has previously been described. The seat is connected to all fourcams. As before, the connections do not restrict movement of the seat inrelation to the cam movements. They only act to retain the seat againstaccidental disconnection from the cams.

In an alternate construction, at least one protrusion/connection memberis used to interface with at least one set of guide tracks. In thisconstruction it is preferred that there are two guide tracks per cam.(The same can be achieved with at least one guide track.) However, itcould also be each side, each having a different or the same outerprofile and each having a different entry interval for the protrusionsfrom each cam. The guide tracks can also feature grooves as well as, orinstead of open and/or closed channel guide tracks. The connectingmember can vary in length, dynamically or set at certain distances awayfrom the cam face to suit interaction with open or closed channels. Thechannels are of no fixed profile or depth or width, as are theconnecting member. However, it is preferred that the profile is straightor taper-sided, with the connecting member and open/closed channelprofiles preferably having the inverse to the shape of the other.

As the cams start to operate and the seat begins to lift in a verticalmanner; connecting members now start to interact at different settimings and intervals with the correct open or closed channels, on theseat. The width of open or closed channel and the dimensions of theconnecting members are such that no contact occurs unless a force isplaced on the seat such that it is in danger of accidentally beingdisconnected from the cams or relative horizontal movement, inparticular a movement that would potentially see the seat dislodged fromany one of the cams.

The design of these extra open or closed channels is such that theypreferably only operate within a first vertical section of the liftuntil the front cams tilt connection member 202 has engaged within thetilt member receiver 208. After which point the system operates exactlyas has previously been disclosed i.e. the front cams control the pivotpoint of the tilt and can move in either direction. In effect this meansthe seat gains an extra two axes of movement: the whole seat canactively travel forwards and backwards and the just the front canactively travel forwards and backwards. Furthermore, these movements areachieved in a safe manner with little efficiency losses due seatretention mechanisms.

The channels can be varied, as can the position of the connecting memberwith which they interact. The extra guides and/or open and/or closedchannels can interact with either the rear set of cams 204 or the frontset of cams 202 or both.

Thus, the system is widely variable, very smooth, energy efficient, andable to be adapted to any environment or user constraint with littleenergy wastage on counter loading of the seat.

The slides 210, 212 with which the cams 202, 204 operate in exactly thesame way as has previously been described in other embodiments, notingthat 210 and 212 and the same as has been described for 810 and all itsinteractions. The cams 202,204 have exactly the same described featuresand make up as 104, as described above.

The at least one carriage, continuous or non continuous shafts, rollers,bearings (roller type and/or plain) and cam blade can be securelyretained, preferably by interference fit between shafts andcorresponding recesses or holes on each part and or more traditionalmechanical means via employment mechanical retention methods such asthreaded members, threaded and locking members and members that exhibita inner diameters below the outer diameter of the plain shaft and anouter diameter in excess of the plain shaft and used in relation totheir radial force exertion for position and interactive stability andfitted in a groove or undercut to the plain shaft and or further membersretained via a press fit, with the rollers having free rotation, can allbe used with the quad cam system described above (the secondembodiment).

A third embodiment is depicted in FIGS. 14A and 14B. FIG. 14A shows aside view and FIG. 14B shows a plan view. This version uses a singlemotor to power one pair of cams 302 and 308. Cams 302 are locatedtowards the front and cams 308 are located towards the rear, with eachfull lift mechanism comprising two mechanism sets i.e. a front and arear cam drive by one motor at the left side of aperture 102 and thesame at the right side of aperture 102.

This embodiment uses a split rack/shaft mechanism comprising the maincomponents of the direction retainer gear 306, the sprung gear retainer310, the mechanical or natural spring 312, the dual arm drive rack nut322 with split rack/shaft section 314/318, the lead screw 316 and themotor 326. These main components with some sub components (described inmore detail later) allow the mechanism to drive two cams with differentstroke lengths from a single drive source. The drive rack nut in thisembodiment has preferably two integral drive racks located at each sideof the nut, as can be observed from FIGS. 14A and 14B.

The cams in this embodiment have the same features and characteristicsas those discussed in 104, 202 and 204. In FIG. 14A one side of themechanism is depicted, the other mechanism is exactly the same, yetmirrored around the seat centre line with the cams and subsequentcomponents and members located on corresponding i.e. opposite sides tothat shown. The function of each side is exactly the same and all thesame components and members are used in the same way; as is better shownin FIG. 14C.

The cams as described in described above in relation FIG. 13A-13C, workin opposite directions and thus to achieve this via one motor, only onecan be directly driven by the drive rack nut 322. In this case the largerear cam is directly driven. The small front cam is driven via a drivegear 306. As has previously been described, the cams have an integrateddrive gear, the large cam gear meshing with the drive rack nut 322 andin particular the toothed drive rack section 318, whilst the small frontcam integrated gear meshing with the secondary gear 306 which in turnmeshes with the drive rack nut 322 and subsequent drive rack or splitrack/shaft section 314.

The components aft of the cams will now be described, detail of each canbe transposed. Firstly, cams with integrated gears have been welldescribed above. However, cam and drive gear location has not beendiscussed. When a drive gear is used in the lifting mechanism the gearis placed in an offset position to avoid clashes with the drive rack nutand drive rack section 314/318 and 322 respectively and any of itscomponents, the offset position being described as vertical differencein horizontal centre lines between the integrated cam drive gear and thedrive gear itself.

This format is an important consideration as it means that the effectivehorizontal distance used to mesh the gears is reduced. Preferably thesmaller front cam gears are smaller than the large rear cam gear, thusthe effective transposed combined depth is no greater than the largesingular integrated rear cam drive; thus a compact system can beproduced.

The drive rack nut 322 will now be described, this has also been welldescribed in previous embodiments and preferably consists of severalintegrated parts, a threaded insert of the same thread as the lead screwthread with which it meshes with the two drive racks, located eitherside of main nut body.

The drive rack sections 314 and 318 are preferably an integrated featurestemming from route source manufacturing. The location of the rackdrives can be placed in any position around the circumference of themain body relative to the lead screw. This is true in all applicationand can be observed via FIG. 7A and FIG. 14A. From the preferredembodiment the rack 136/136 a is positioned above the lead screw whereasin FIG. 14A, the rack is located at the side and at the same verticallevel as the lead screw; this is true for the racks located at eitherside i.e. for front and rear cam/drive gear meshing.

Each of the arms of the rack drive can have different main parameters.Firstly the length and overall base shape and or form can be different.For example, one rack can exhibit a round base form, whilst the otherrack can exhibit an oval or square profile. Further, each can exhibitdifferent gear tooth patterns/configuration and can either have teethformed with original source manufacture or post source manufacturing cutteeth and the racks can differ dimensionally.

The main difference between the drive racks sections is that of theaddition of the sprung gear retainer 310 and natural or mechanicalspring 312. The retainer is used to achieve the main usage parameters ofthe system and works to engage with the drive gear 306 to retain thesmall front cam in a set position. In this embodiment, the drive racksection 314 exhibits a raised section on which a mechanical spring isremovably or permanently attached. Other methods of both exerting and/orresisting the travel of the retainer along its given axis may be used,such as resilient means including elastomers, rubbers or polymer basedmaterials.

The sprung gear retainer is located on the shaft, preferably this unitis made in one piece, although the unit can be made from a number ofcomponents which are removably or permanently attached i.e.welding/bonding agent or via inference fits and or mechanical retentionmeans such as threaded members.

The unit can incorporate roller type or plain bearings and/or linear orrotational slides within its bore which will contact directly to thesurface of the drive rack. The bearings and/or slides can be coated withfurther friction reducing material and can be removably or permanentlyattached. The action of the spring is to exert a force on the springretainer which advances the retainer towards the drive gear. An increasein the shaft diameter retains the sprung gear retainer in a set forwardposition. The set position can alter the small front cam stroke.

This alternation and therefore the original set point can beaccomplished in many ways. The preferred option is an increased sectionintegral to the drive rack and/or split drive rack section at routesource of manufacture. This is placed at the front most point possibleand then for every subsequent alteration a separate member of raisedsection, equal or not equal to the outer diameter of the integral raisedsection, is removably or permanently attached to the drive rack and/orsplit drive rack section 314, between the sprung gear retainer and theintegral raised section and thus alters the effective stroke distance ofthe sprung gear retainer and the point at which it interacts with thedrive gear.

Manufacture of the raised section can be combinations or individuallyadministrated processes, preferably these include the application ofcontinuous members via interference fits, continuous members withsignificantly smaller inner diameters (in comparison to the drive racknut/drive rack split/shaft nut) and thus implying that the drive rackcan be manufactured in a number of separate sections and non-continuousraised sections with mechanical fit and closure and all preferably withor without threaded members, welding, keyed sections, interference orpressure/press type jointing and/or bonding to hold the various/relativemembers in the desired location or manner.

In an alternate construction the raised section can be located postroute source of manufacturing by a number of different processes. Thepreferred processes for the raised section location can be combinationsor individually administered processes and are centred on continuousinference fits, undersized raised section inner diameter with or withoutsprung members and with or without drive rack undercuts, non continuousraised sections with mechanical fit and closure all with or withoutthreaded members.

It is preferred that the raised section is removably attached and thusif the effective stroke distance of the sprung gear retainer requiresalternation, the work can be completed cost effectively via the use ofstandard continuous differing thickness annular ratio members.

In the case of the drive section 318, this is an integral part of themain drive nut 322. The moulded and/or cut gear toothed section can bethe full length or a partial length of the rack. The gear teethcharacteristics are preferably the same as the other system components,although if required the each cam and integrated gear and thus the driverack, can have the same teeth characteristics to all other gear toothedmembers, for example one the other cam gear and drive rack sets.

Both drive racks are removably or permanently attached to the main bodyof the drive nut, which houses a removably or permanently attached orintegrated threaded insert member of a different material. The insertmember allows location onto the lead screw via meshing of threads as haspreviously been described in other embodiments.

The lead screw can be removably attached or permanently held in positionpreferably by roller type of plain bearings/bushes, the bushes/bearingspreferably being located on the lead screw in one of three places, 304,316 a and 328. The surfaces at these points are preferably coated in afriction reducing material substance and as in all embodiments andconstructions are of a suitable surface finish for the prescribed usage.

At least one gear is located on the lead screw. The gear can bepermanently or removably attached to the drive rack and/or split driverack section preferably via mechanical means such as plain or expandablepins and or circlips, both with interference fits and both can bebonded. Although it is also preferred that keys and threaded members canbe utilised for gear retention purposes.

The last part of the system is the motor and gear arrangement. Thearrangement of the motor with integral gear box connected to a drivecoupling has been described in relation to 124 and 130 from FIG. 8 andthe parameters of a keyed and mechanical connection are directlytransferable to this application as are the methods described for gearattachment to the lead screw above, for example keyed and pinned, withexpandable or plain pin and or cirlips, both with interference fits andboth can be bonded. Both the motors 326, 320 are held in position viaattachment to the seat unit 12.

The system is operated by a control unit that interprets inputs from anumber of sources such as sensors and operator/user instructions. Thecontrol unit allows power from a power source to flow to the motors in amanner that controls the speed of rotation and power available. Therotation of the motor drives the gear 320, which in turn is meshed withand drives the gear 324. This gear then drives the lead screw which inturn drives the drive rack nut as a result of the meshed relationshipand as a result of the application of power to the motor.

As the drive rack nut advances, the split drive rack/shafts advance andcause either the large cam gear 318 to rotate or the drive gear 306 torotate. The large cam gear 318 results in large cam rotation whilst thedrive gear 306 results in the rotation of cam 302.

The spring retainer 310 is preset at certain distances by a stop memberwhich is on or art of the split drive rack/shaft on which the retaineris located, as has previously been described. As the rack shaftadvances, the drive rack section 314 meshes with the gear eitherintegral to the cam or, as in this embodiment, meshed with the cam drivegear 306 to provide a difference in rotation between the front and rearcams from the same drive.

As the rack continues to advance, the sprung retainer section eventuallymeshes with the drive gear 306 and thus holds it in position; in adifferent embodiment the drive retainer can be applied directly to theintegrated cam gear. The slide part continues to advance through thesprung retainer. This allows the mechanism of two cams with differentstroke and rotational parameters and characteristics to be driven fromthe same motor.

The sprung retainer 308 is pre-set at certain distances by a stop memberwhich is on or part of the split drive rack/shaft on which the retaineris located as has previously been described. As the rack/shaft advances,the rack section meshes with a gear integral to front cam 302 andprovides rotation to cam 302. Thus, this embodiment allows a singledrive source to drive two cams, with each cam being required to rotateby a different amount.

A fourth embodiment is depicted in FIGS. 15A, 15B and 15C. Thisembodiment incorporates two separate drive systems for a front cam 402and a rear cam 404. The system is such that the all aspects of all otherembodiments as described in the text can be utilised for all components,for example the cams referenced 402 and 404 and have all the samefeatures as those of 104, 302 and 308 and or the references to any otherembodiment for the lead screws 140 and 316.

This embodiment differs from the other embodiments by the system layoutand the dual feature usage of the integrated cam gear 404 and drive gear414. The first difference to the previously described systems is theindividual cam drives. This means that each lifting cam has anindividual motor for its power source. This yields large flexibility inthe system meaning that each of the cams can be precisely controlled andthe seat can then be tilted and rotated side to side; for example,“pitch and roll” where tilt is equal to pitch and roll is equal to sideto side movement. This can assist compensate or “shim” certain users andparticularly stroke victims. This pitch and roll can be achieved by allembodiments and constructions.

One side of the lift system is depicted. As with the embodiment of FIGS.14A and 14B preferably two sets are required for a complete liftingsystem placed either side of the aperture 102. Thus the one set can bemirrored to gain an impression of the other set, the large cam alwaysremaining on the outside edge, as can be seen in FIG. 15C.

Discussing each sub system in turn, starting with the small front cammechanism, a cam with integrated gear 402 is provided. An integrateddrive rack 408 and drive rack nut 408 a, a lead screw preferablysupported at 412, 412 a, a lead screw 422, two drive gears 424, 426 andfinally a motor 420.

The lead screw is held in position by the seat unit 12 and uses rollertype or plain bearings removably or permanently attached to rotate withminimum friction. The cam drive rear is meshed to the drive rack, thisis integrated with the drive rack nut and the two components areremovably or permanently attached either via the route sourcemanufacturing i.e. casting or via a post process preferably via weldingand or mechanical/threaded fixings and interference fits.

Held captive within the drive rack nut is a threaded insert, the insertmeshes with the lead screw thread, both preferably being the same pitchand thread designation. The insert is removably or permanently heldcaptive within the drive rack main body. The gear on the end of the leadscrew is removably or permanently attached via mechanical and/or othermeans, preferably via a keyed and/or expandable or not expandable pinand/or a threaded member.

The leadscrew gear is meshed with the gear 426 which is removably orpermanently attached to the integrated motor and gear box shaft viamechanical and/or other means, preferably via a keyed and/or expandableor not expandable pin and or a threaded member.

The large rear cam mechanism has a cam with integrated gear 402, an camdrive gear, 414, an integrated drive rack 432 and drive rack nut 432 a,a lead screw preferably supported at 410 and 410 a, a lead screw 428,two drive gears 430 and 436 and finally a motor 438 and a special rigidcased linear and rotational plain bearing 434.

The lead screw is held in position by the seat portion 12 and usesroller type or plain bearings removably or permanently attached torotate with minimum friction. The cam drive rear is meshed to the driverack, this is integrated with the drive rack nut and the two componentsare removably or permanently attached either via the route sourcemanufacturing i.e. casting or via a post process preferably via weldingand or mechanical/threaded fixings and interference fits.

Held captive within the drive rack nut is a threaded insert, the insertmeshes with the lead screw thread, both preferably being the same pitchand thread designation. The insert is removably or permanently heldcaptive within the drive rack main body. The gear on the end of the leadscrew is removably or permanently attached via mechanical and/or othermeans, preferably via a keyed and/or expandable or not expandable pinand/or a threaded member.

The leadscrew gear is meshed with the gear 436 which is removably orpermanently attached to the integrated motor and gear box shaft viamechanical and/or other means, preferably via a keyed and/or expandableor not expandable pin and/or a threaded member.

An additional large gear 414 is provided to drive the rear cam 404. Thecam is driven through this gear 414, which allows the speed and torquecharacteristics of the rear cam 404 to be determined by the choice ofthe large gear 414. The centre line of the large gear 414 can be aboveor below that of the gear attached to cam 404. The size of the largegear can give a speed or effective torque alteration within the system.Choice of an appropriate large gear size can therefore adapt thisembodiment to a number of drive configurations.

The large gear has a further purpose in that it is able to reduce theeffective stroke length of the drive rack and thus enable a greaternumber of packaging alternatives for the mechanism. The stroke lengthalso depicts the possible pitch of thread on the leadscrews and thus thesize of the gear can affect the whole system. This includes the speed ofthe motor and through to motor selection through all other aspectsincluding the motor gear box, gear sizes and ultimately cam size. Thelarger gear and the location of the gear will furnish the drive rackwith a reduced or increased stroke for the same actual rotation of acam; thus the rack and the gears can be matched to suit any pitch oflead screw.

The large gear of this embodiment can be applied to any of the otherembodiments if desired. Likewise, an additional gear could also be usedto drive the front cam 402.

The rack drive can be manufactured of a flexible material and this canbe applied to any other embodiment if desired.

The motor 438 and 420 power the respective the systems as described andthe action results in rotation of the cams, typically through the seriesof meshed interactions. It is important to note that to achieve thereverse rotation on one cam, the drive rack nut is located at thefurthest point of the lead screw with the motor running in reversedirection compared to previously described embodiments and in thisembodiment compared to the other motor. It is also important to notethat the motor for the small cam has been orientated differently toother referenced systems; this orientation as with any other orientationcan be applied to other systems and embodiments if desired.

The roller assembly is positioned such that no undulation is caused tothe seat during lifting or any other operation. A roller assembly caninclude at least one roller type or plain bearing, at least one rollerand at least one shaft.

The thick section associated with housing the rollers can be continueddown the full length of the cam blade, or stop at any point along itslength, or no such thick section housing could be required.

The cam can be made from laminate or differing materials that combineproperties of strength and friction reduction such as a metallic coresurrounded by a polymer based outer surface.

In a further construction/embodiment the carriage unit is split into twosections, one section is a free rotation section and the other ispermanently and/or removably fixed to at least one cam and/or cam bladeand is not able to be rotated. The fixed section has a continuous/noncontinuous raised material section that protrudes from the base of thesection to form a bowl like shape. The base can be concave of convex andthe raised sections can be perpendicular to the base, although the anglebetween the base and the raised section can increase and decrease. Forexplanation, the walls can point outwards or inwards and the base has aprotrusion in the centre that is preferably circular and can be hollowor solid.

The mating unit is also as per that of the fixed section as described,it features continuous/non continuous raised material section thatprotrudes from the base of the section to form a bowl like shape. Thebase can be concave or convex and the raised sections can beperpendicular to the base, although the angle between the base and theraised section can increase and decrease. For explanation, the walls canpoint outwards or inwards and the base has a protrusion in the centrethat is preferably circular and can be hollow or solid and is free torotate.

The free rotation section or mating section either assembles to thefixed section on the inside or the outside. In the case of the at leastone section fitting on the inside, the free section will carry the atleast one roller/roller assembly and/or shaft assembly on the remainingexternal surface, this will be the external part of the base. In thecase of fitting of the free rotation section, the at least oneroller/roller assembly and/or shaft assembly are fitted to the raisedsection external surface.

The assembly then takes the usual seat carriage unit emphasis in thatthe multiple or single roller/roller assemblies and or shaft assembliesset relative to the axial rotation centre of the at least one cam andthus set the effective profile of the at least one cam and seatdisplacement. A track or covering can be placed over the at least oneroller/roller assemblies and or shaft assemblies to form a track orcovering that can be rigid or flexible, continuous and or non-continuousand held moveably captive or non-captive with the confines of thecarriage unit can be fitted in this configuration.

The protrusions in each section can carry bearings to allow the freesection to rotate, the bearings can be roller type and/or plainbearing/bushes. The bearings are attach permanently or removably viainterference fit as are the two sections of the carriage units via thesolid and/or hollow protrusions.

At least one track/conveyor on the at least one carriage unit allows theeffective movement of the at least one cam against the seat with minimalfriction and as little resultant undulation as possible; the trackallowing a greater pitch (defined as the distance between relativemembers centres) between the at least one roller and/or roller assemblyand/or shaft assembly.

In a further embodiment the carriage unit can be mounted in a sprungfashion, using mechanical and/or polymer based and/or rubber materialsand design solutions, it is also possible to mount all the at least oneroller/roller assembly and/or shaft assembly in a sprung fashion usingsimilar means and this is applicable to all embodiments andconstructions.

In all embodiments the motor 128, 326, 412 is preferred to feature anintegral reduction gear box to reduce the final rotational speed of themotor and increase permissible torque output from the motor device.

In all embodiments and or constructions, all referenced grooves and openand/or closed channels are of no fixed profile or depth or width;however, it is preferred that the profile be straight or taper sided andany interacting member preferably having the inverse to the shape/formatof the groove and open and/or closed channel.

In all embodiments the roller can either rotate about the bearingrelative to the shaft or the roller and bearing can rotate about theshaft.

In all embodiments the roller and/or the bearing, whether plain orroller type can be set such that the outer surface or outer diameter arepositioned above the cam and or cam blade.

In all embodiments the roller, can be removably attached or permanentlyattached.

In all embodiments the roller type of plain bearing can be removablyattached or permanently attached to the cam and/or the cam blade.

In all embodiments the shaft can be removably attached or permanentlyattached to the cam and or the cam blade.

In all embodiments the cam and cam blade can be removably attached orpermanently attached to the cam blade or the cam, respectively.

In all embodiments the roller carriage can be removably attached orpermanently attached to the cam and or the cam blade.

In all embodiments the cam can be any shape or form depending on thedesired lift characteristics.

A fifth embodiment is depicted in FIG. 16. In this embodiment the cam704 interfaces with the seat by a slider or track system 700 and is asdescribed above in relation to 810. 702 and 706 are to highlight thedifferent profiles possible for any cam edge. Preferably the cam edgesare tapered 706. In all cases they are made to suit the seat trackinterface for smooth non-undulating operation that is safe in use and ofthe correct function. They are also chosen to reduce frictional loads.

A sixth embodiment of the present invention is depicted in FIGS. 17 to20. This uses a mono-chassis lifting pod. The mono-chassis pod is uniquein medical applications; the pod is the main structural part of anydevice that it is used within. The main devices where the pod would beused are, dynamic commodes, static commodes, wheelchairs, transferchairs etc, all the uses representing the second unique feature i.e.multi-functionality; see FIG. 17.

The pod can house a motor and cam lifting mechanism in order that liftcan be applied to a seat if required and if incorporated with anotherside pod and joined via a backrest; see FIG. 18.

The pod also includes an integral backrest support, a feature that hasnever previously been observed in the medical sector.

An internal braking mechanism is provided, a feature of which is thatthe pod is designed such that the wheels can be retracted—this iscompleted via a sprung or other such mechanism; see FIG. 20.

The embodiment has the ability to use a simple “snap” or sliding fit forthe actual backrest; noting the pod is always used in two halves, eachhalf being restrained by the association with the backrest.

The pod of this embodiment is also able to take a special medical powerand motion transmission cartridge; the cartridge is located in thedevice and can provide motion of the various mechanisms i.e. the camlift systems.

A seat can be incorporated into the system as per FIG. 17 ifrequired—the cam lift (FIG. 18) can be used to raise the seat.

In an alternate embodiment, the seat is supported at its front by a pairof cams instead of the lift actuators of the first embodiment.

In a further alternate embodiment, other driving mechanisms are used todrive the rack and the cam. This can include additional gears to allowrotation of the cam in either direction without requiring that therotation direction of the electric motor is altered.

In another alternate embodiment, different lift patterns are used. Theseinclude: a combination of lift and tilt simultaneously; tilting the seatalone and simply raising the seat.

In another alternate embodiment, the seat frame does not incorporate abackrest.

In an alternate embodiment, friction reducing coating or materials areused.

In an alternate embodiment, the seat has integral armrests.

In an alternate embodiment, the frame includes push/pull/locationhandles located in selected areas.

In an alternate embodiment, connection points are provided on the frame.

In an alternate embodiment, the frame comprises removably attachedcomponents.

In an alternate embodiment, footrests are incorporated into the frame.

In an alternate embodiment, the frame houses electronic components.

In an alternative embodiment a disposable or permanent cover in part orwhole can be placed over the seat, seat frame, backrest and seatportion.

In an alternative embodiment a removably attached soils reciprocal canbe permanently or removable attached to the seat portion and or thedisposable or permanent cover.

In still further alternate embodiments, a large variety of alternativeways of realising the invention can be achieved. In these embodiments,belt drives, v belt drives, meshed gears, vertical lift, pivot bars,shaft, gears, drive mechanisms, motion exciters, seals magnets,solenoids, sliders, grooves, pins and grooves, gear teeth, belts,toothed belts, v, belts, bearings,vertical/rotation/vertical/lift/tilt/linear/cam drive/motion exciters,sprockets or power/motion transmitter transfer components, or chains areutilised.

All the above embodiments are particularly well suited to use in medicaltransfer chairs, other mobility applications, and commodes. It will beappreciated that numerous other minor modifications will suggestthemselves to the person skilled in the art. This description should notbe seen as limiting the scope of the invention, which is defined by theappended claims.

1. A riser seat for assisting a person from a sitting position to astanding position, comprising: seat frame; a seat comprising upper andlower surfaces, the seat being movable between first and secondpositions; and a cam arm pivotably mounted with respect to the seatframe and having a camming surface movably engaged with the seat and thecam arm moves the seat along a movement profile between the first andsecond positions, wherein the camming surface defines the movementprofile and the camming surface moves tangentially relative to the lowersurface of the seat to move the seat between the first and secondpositions.
 2. The riser seat of claim 1 wherein the camming surface isslidably engaged with the lower surface of the seat.
 3. The riser seatof claim 1 wherein the cam arm is coupled to the seat frame at a pivotpoint, and the cam arm pivots about the pivot point.
 4. The riser seatof claim 3 further comprising: a gear coupled to the cam arm and coaxialwith the pivot point; and a rack in meshed engagement with the gear suchthat translation of the rack results in the cam arm pivoting about thepivot point.
 5. The riser seat of claim 1 further comprising a linearactuator coupled to the seat frame at a front end of the seat frame, thelinear actuator terminating in a top connection member that engages thelower surface of the seat at a front end of the seat, the linearactuator moving the front end of the seat between the first and secondpositions.
 6. The riser seat of claim 5 further comprising a pivot thatconnects the top connection member to the seat, the seat pivoting aboutthe pivot.
 7. The riser seat of claim 6 wherein the cam arm and thelinear actuator are independently movable.
 8. The riser seat of claim 1wherein the cam arm is a first cam arm and the riser seat furthercomprises a second cam arm pivotably mounted with respect to the seatframe, the second cam arm having a camming surface movably engaged withthe seat and configured to move the seat between the first and secondpositions, wherein the camming surface moves tangentially relative tothe lower surface of the seat when the seat is moved between the firstand second positions.
 9. The riser seat of claim 8 wherein the first camarm and the second cam arm are coupled to the seat frame at a pivotpoint, and the first cam arm and the second cam arm pivot about thepivot point.
 10. The riser seat of claim 8 wherein the first cam arm iscoupled to the seat frame at a first pivot point and the first cam armpivots about the first pivot point, and the second cam arm is coupled tothe seat frame at a second pivot point and the second cam arm pivotsabout the second pivot point.
 11. The riser seat of claim 1 furthercomprising a connection member on the cam arm, wherein the connectionmember engages the seat to maintain engagement between the cammingsurface and the lower surface of the seat.
 12. The riser seat of claim11 wherein the seat further comprises a guide track, the connectionmember of the cam arm engages the guide track of the seat.
 13. The riserseat of claim 1 further comprising an aperture through the seat suchthat the seat functions as a commode.
 14. The riser seat of claim 1wherein the lower surface of the seat further comprises a track disposedalong the lower surface, the camming surface contacting the track, thetrack facilitating the tangential movement of the camming surfacerelative to the lower seat.
 15. The riser seat of claim 14 wherein thetrack comprises a friction reducing material.
 16. The riser seat ofclaim 14 wherein the track comprises at least one roller.
 17. The riserseat of claim 1 wherein the camming surface comprises a roller orbearing that engages the lower surface of the seat.
 18. The riser seatof claim 1 wherein the cam arm further comprises a plurality ofrotatably coupled cam sections.
 19. The riser seat of claim 18 whereinthe cam arm further comprises a center shaft and the plurality ofrotatably coupled cam sections are mounted to the center shaft such thatthe cam sections rotate about the center shaft.
 20. The riser seat ofclaim 18 wherein each of the plurality of cam sections further comprisesa peg and a slot that receives a peg of an adjacent cam section, whereinthe interaction of the peg and the slot restricts rotational movement ofthe plurality of cam sections.
 21. A riser seat for assisting a personfrom a sitting position to a standing position, comprising: a seatframe; a seat comprising upper and lower surfaces, the seat beingmovable between first and second positions; first and second cam armspivotably mounted with respect to the seat frame, each of the first andsecond cam arms having a camming surface movably engaged with the seatwherein the camming surface moves tangentially relative to the lowersurface of the seat when the seat is moved between the first and secondpositions; and first and second linear actuators coupled to the seatframe, wherein each of the first and the second linear actuators engagethe seat at a front end of the seat; wherein coordinated movement of thefirst and the second cam arms and the first and the second linearactuators moves the seat between the first and second positions.
 22. Theriser seat of claim 21 wherein the first cam arm, the second cam arm,the first linear actuator, and the second linear actuator are eachindependently movable.
 23. The riser seat of claim 22 further comprisinga first pivot that connects the first linear actuator to the seat and asecond pivot that connects the second linear actuator to the seat, theseat being pivotably moveable about the first pivot and the secondpivot.
 24. The riser seat of claim 23 wherein the coordinated movementof the first and second cam arms and the first and second linearactuators moves the seat along a movement profile wherein the movementprofile lifts and tilts the seat.
 25. The riser seat of claim 24 whereinthe movement profile further pitches the seat to a first side of theseat.
 26. The riser seat of claim 23 wherein the first cam arm iscoupled to the seat frame at a first pivot point and the first cam armmoves about the first pivot point, and the second cam arm is coupled tothe seat frame at a second pivot point and the second cam arm movesabout the second pivot point.
 27. A method using the riser seat of claim21 to move a person sitting on the seat from a seated position to astanding position, comprising: simultaneously moving the first andsecond linear actuators and the first and second cam arms to lift theperson in a seated position; maintaining a position of the first andsecond linear actuators; and moving the first and second cam arms totilt the person into a standing position.
 28. The method of claim 27further comprising: simultaneously moving the first linear actuator andthe first cam arm such that a first side of the seat is raised above asecond side of the seat such as to pitch the seat in the direction ofthe second linear actuator and the second cam arm.
 29. A riser seat forassisting a person from a sitting position to a standing position,comprising: a seat frame; a seat comprising upper and lower surfaces,the seat being movable between first and second positions; and first,second, third, and fourth cam arms pivotably mounted with respect to theseat frame, each of the first, second, third, and fourth cam arms havinga camming surface movably engaged with the seat wherein each of thecamming surfaces move tangentially relative to the lower surface of theseat when the seat is moved between the first and second positions;wherein coordinated movement of the first, second, third, and fourth camarms moves the seat between the first and second positions.
 30. Theriser seat of claim 23, wherein the first, second, third, and fourth camarms are each independently movable.
 31. The riser seat of claim 29,further comprising a first pivot point that couples the first cam arm tothe seat frame, a second pivot point that couples the second cam arm tothe seat frame, a third pivot point that couples the third cam arm tothe seat frame, and a fourth pivot point that couples the fourth cam armto the seat frame.
 32. The riser seat of claim 29 wherein thecoordinated movement of the first, second, third, and fourth cam armsmove the seat along a movement profile that lifts and tilts the seat.33. The riser seat of claim 32 wherein the movement profile furtherpitches the seat to a first side of the seat.
 34. A method of using theriser seat of claim 29 to move a person sitting on the seat from aseated position to a standing position, comprising: simultaneouslymoving the first, second, third, and fourth cam arms to lift the personin a seated position; maintaining a relative position of the first camarm; simultaneously moving the second, third, and fourth cam arms tolift the person; maintaining a relative position of the second cam arm;simultaneously moving the third and fourth cam arms to lift the person;maintaining a relative position of the third cam arm; and moving thefourth cam arm to tilt the person into a standing position.
 35. Themethod of claim 34, further comprising: simultaneously moving the first,second, and third cam arms such that a first side of the seat is raisedabove a second side of the seat such as to pitch the seat in thedirection of the fourth cam arm.
 36. An adjustable position riser seatcomprising: a seat frame; a seat comprising upper and lower surfaces,the seat being movable between first and second positions; and a cam armpivotably mounted with respect to the seat frame and having a cammingsurface movably engaged with the seat and configured to move the seatalong a movement profile between the first and second positions, whereinthe camming surface defines the movement profile and the camming surfacemoves tangentially relative to the lower surface of the seat to move theseat between the first and second positions.
 37. An adjustable positionriser seat comprising: a seat frame; a seat comprising upper and lowersurfaces, the seat being movable between first and second positions; afirst cam arm pivotably mounted with respect to the seat frame and thefirst cam arm having a camming surface movably engaged with the seat andconfigured to move the seat between the first and second positions; anda second cam arm pivotably mounted with respect to the seat frame andthe second cam arm having a camming surface movably engaged with theseat and configured to move the seat between the first and secondpositions; wherein the camming surfaces move tangentially relative tothe lower surface of the seat when the seat is moved between the firstand second positions.
 38. The riser seat of claim 37 wherein the firstcam arm and the second cam arm are coupled to the seat frame at a pivotpoint, and the first cam arm and the second cam arm pivot about thepivot point.
 39. The riser seat of claim 37 wherein the first cam arm iscoupled to the seat frame at a first pivot point and the first cam armpivots about the first pivot point, and the second cam arm is coupled tothe seat frame at a second pivot point and the second cam arm pivotsabout the second pivot point.